The present invention relates to improvements in testing of rod-shaped articles which constitute or form part of smokers' products. More particularly, the invention relates to a novel and improvement method and to a novel and improved apparatus for testing successive plain or filter tipped cigarettes, cigars or cigarillos, cheroots, filter rod sections or similar rod-like articles (which may consist of natural or reconstituted tobacco, tobacco substitutes, filamentary and/or granular filter material and/or a combination of such substances) while the articles are in the process of moving or about to move sideways, i.e., substantially at right angles to their respective axes.
It is well known to test rod-shaped articles which constitute or form part of smokers' products (for the sake of convenience, such articles will be referred to as cigarettes with the understanding, however, that the invention can be practiced with equal advantage in connection with all or nearly all types of rod-like smokers'products) before the cirgarettes are introduced into packets, boxes or other types of containers for storage or for sale to customers. The testing is intended to uncover the presence of wrappers which exhibit holes, unsatisfactory seams, frayed ends and/or a combination of two or more such defects. As a rule, the testing operation is carried out pneumatically, for example, by establishing a pressure differential between the interior and the exterior of the wrappers of successive cigarettes. If a wrapper exhibits one or more defects of the above outlined character, monitoring of the pressure within or around the defective wrapper will reveal the presence of such defect or defects, and the corresponding cigarette is thereupon segregated from the remaining (satisfactory) cigarettes. The arrangement may be such that the pneumatic testing apparatus generates a signal when the permeability of the wrapper of a cigarette is excessive and/or insufficient, and the signal is used for automatic segregation of the corresponding cigarette. Reference may be had to commonly owned U.S. Pat. Nos. 3,783,677 and 3,962,906 respectively granted Jan. 8, 1974 and June 15, 1976 which show a few recent types of pneumatic testing apparatus for cigarettes or the like.
A drawback of pneumatic testing apparatus is that they are incapable of detecting each and every defect in or on the wrapper of a cigarette or the like. For example, a pneumatic testing apparatus will fail to detect a hole which happens to be plugged, either entirely or in part, by a fragment of tobacco. The hole can be large enough to be readily detectable with the naked eye; nevertheless, even a highly sensitive pneumatic testing apparatus is unlikely to detect such hole if the latter is accidentally sealed by a fragment of a tobacco rib or the like.
A pneumatic testing apparatus is further unlikely to ascertain the presence of certain defects which do not unduly affect the quality of cigarettes but detract from the eye-pleasing appearance of such smokers' products. For example, pneumatic testing apparatus will not detect the presence of a tobacco crumb between the overlapping edge portions of cigarette paper which forms the wrapper, i.e., the presence of a crumb in the seam of the wrapper even though such crumb causes pronounced deformation (bulging) of the corresponding portion of the seam.
Another defect found in cigarettes, especially filter cigarettes, which is not likely to be detected by resorting to a pneumatic testing apparatus is the presence of so-called lips or flags on the convoluted uniting bands which connect plain cigarettes with filter plugs. As a rule, a filter tipping machine makes filter cigarettes of double unit length; each such cigarette is thereupon severed midway between its ends to yield two filter cigarettes of unit length. The cut is made centrally across the convoluted (tubular) uniting band which is used to connect a filter plug of double unit length with two plain cigarettes of unit length. If the uniting band is not applied in an optimum position, it is likely that one of its edges (namely, one of those edges which extends in parallelism with the axis of the filter cigarette of double unit length) will project beyond the confined filter plug and will form a lip which is detectable by the smoker and is likely to lead to detachment of the filter plug from the plain cigarette or cigarettes. The presence of the just discussed flags or lips is often caused by unsatisfactory coating of one side of the uniting band with a suitable adhesive.
British Pat. No. 1,028,372 discloses an apparatus for optically scanning the wrappers of cigarettes or the like. The apparatus of this patent embodies means for withdrawing successive articles to be tested from their normal path, for inserting successively withdrawn articles between two rotating drums, and for optically scanning the articles between the rotating drums. The patented apparatus exhibits several serious drawbacks, especially as concerns the complexity of the withdrawing means. Moreover, the two rotating drums perform no function other than to rotate the articles during optical scanning, and the apparatus occupies a substantial amount of space mainly because it utilizes several components (such as the two drums and the withdrawing means) which serve no other purpose but to allow for optical scanning of articles. Therefore, the just discussed patented apparatus failed to gain widespread acceptance in the industry.
U.S. Pat. No. 3,854,587 discloses a ring-shaped optical testing head for a continuous wrapped tobacco filler which is caused to pass axially through the testing head. During such transport of the wrappecd filler, the optical components on the testing head scan the wrapper of the filler and generate signals which, when indicative of a defective wrapper portion, are used to segregate the corresponding portions of the filler from the remaining (satisfactory) portions. A drawback of such optical scanning apparatus is that the testing operation is carried out too early, i.e., prior to subdivision of the wrapped filler into discrete rod-shaped articles, such as cigarettes or the like. Therefore, and in order to insure segregation of all defective articles (e.g. filter cigarettes of unit length), the apparatus of U.S. Pat. No. 3,854,587 must be followed by a second testing apparatus or the testing operation is unreliable because numerous discrete defective rod-shaped articles are likely to remain undetected prior to insertion into packets or the like.